Depends on the earbuds, I have worn some that allow “pass through sound” meaning even with them in as long as the volume is not too loud it is is just like wearing a stocking cap over your ears in regards to sounds outside of the car, that being said if I need to listen to talk radio from my cell phone in the car I wear only one in the ear that is towards the center of the car.
Problem is the people who don’t have quality earbuds that put other drivers and emergency vehicles at risk, and how do you tell if someone is using a pass through pair or no from a distance? Maybe it’s just me, but I don’t get it, why not just listen to the radio in the car? Personally I can’t even wear a Bluetooth headset because I am all but deaf in one ear and won’t risk not hearing a siren or horn.